Principles of Construction

The SIGMA plate heat exchanger, with its compact construcion, high thermal performance coupled with low investment and operating costs, is the ideal machine for solving thermal problems in a wide range of applications.

The construction kit assembly principle of the SIGMA heat exchanger contains at ist heart, the plate packet. The number of plates, their type ans form is selected to suit the application. Each plate is fitted with a gasket to retain the process media within the plate pack whilst separating them from each other.

The plate pack is fitted into a frame and compressed to ensure adequate sealing. The frame consists of a fixed heat plate (1), a moveable cover (8), carrying bars (9+11) and a number of fightening bolts. The frame can be painted or clad in stainless stell as appropriate.

ldeally, aaa situated on the fixed head plate, but connections can also be made to the moveable cover for multipass designs or to mett customer specifions.


Using the connections on the frame the hot and cold media are conducted into and out of the plate pack. Then fluids pass through the plate pack in the channels between the plates in counter current or in special cases co-current flow. Heat is exchanged through the plates.

Plate heat exchanger SIGMA 114

Variable Flow-Gap

The thermal characteristics and pressure loss develoed by a fluid flowing in the gap between two plates is determined by the pressed profile of the heat exchanger plates. The plates are, therefore, produced in a number of presspatterns.
It is possible to obtain an opitmum match of heat transfer area and pressure drop to the specified duty by combining similar or different plate forms in mixed or block arrangements within the same plate pack.

For viscous fluids or those containing solid particles wide agp SIGMA plates or "free flow" plates which have an unrestricted flow path, are available.


Stainless steels which are corrosion resistant, non toxic, durable, high strength, smooth and easily cleaned have proved the ideal material for making hteat exchanger plates.

Standard materials for SIGMA plates include Stainless Steel 1.4301 (AISI 304), 1.4401 (AISI 316), Titanium- Palladium, Nickel, SMO, Tantalum, Hastelloy, Incolloy and others. The choice is made to match the duty.


Gaskets are used to seal the edges of the plates and form the folw passages. They also ensure complete segregation of the process fluids.
The high quality gaskets can be fitted into the SIGMA heat exchanger plates either by using adhesives or, for some plates, using the SIGMAFIX adhesive free system. Gasket materials commonly uesd include nitrile rubber (NBR), ethylene-propylene rubber (EPDM), butyl rubber (IIR), silicon rubber, chaloroprene rubber (CR, e.g. Neoprene), fluoride rubber (FPM, e.g Viton), chlorosulphonylpoly-ethylene (CSM), e.g. Hypalon) as well as weveral hard, fiber based, asbestos free gaskets. Elastomeric gaskets can, depending on type, be used for process temperatures up to 170”ĘC with the hard gaskets being used up to 300”ĘC.

1. fixes frame plate with connections
2. termainal plate
3. heat exchange plate left
4. heat exchange plate right
5. plate package
6. flow change plate left
7. flow change plate right
8. moving cover
9. upper carrying bar
10. support leg
11. lower carrying bar
12. closing bolt with lock nut